Methods and apparatuses for deploying minimally-invasive heart valves

ABSTRACT

A system for delivering and deploying a self-expandable heart valve includes a deployment mechanism that engages the valve and regulates the rate of expansion of both the proximal and distal ends thereof. The deployment mechanism may include a plurality of distal fingers and a plurality of proximal fingers that engage the end portions of the heart valve. Controlled radial movement of the fingers regulates the expansion of the heart valve such that the proximal and distal ends radially expand at the same rate. A stabilization balloon may be used to axially and radially locate the deployment mechanism relative to the site of implantation. Methods of operation of the delivery and deployment mechanism include regulating the rate of self-expansion of the valve and forcing the valve outward into its fully expanded configuration utilizing the same or different means.

FIELD OF THE INVENTION

The present invention relates generally to medical devices andparticularly to methods and devices for deploying expandable heart valveprostheses especially for use in minimally-invasive surgeries.

BACKGROUND OF THE INVENTION

Prosthetic heart valves are used to replace damaged or diseased heartvalves. In vertebrate animals, the heart is a hollow muscular organhaving four pumping chambers: the left and right atria and the left andright ventricles, each provided with its own one-way valve. The naturalheart valves are identified as the aortic, mitral (or bicuspid),tricuspid and pulmonary valves. Prosthetic heart valves can be used toreplace any of these naturally occurring valves.

Where replacement of a heart valve is indicated, the dysfunctional valveis typically cut out and replaced with either a mechanical valve or atissue valve. Tissue valves are often preferred over mechanical valvesbecause they typically do not require long-term treatment withanticoagulants. The most common tissue valves are constructed with wholeporcine (pig) valves, or with separate leaflets cut from bovine (cow)pericardium. Although so-called stentless valves, comprising a sectionof porcine aorta along with the valve, are available, the most widelyused valves include some form of stent or synthetic leaflet support.Typically, a wireform having alternating arcuate cusps and upstandingcommissures supports the leaflets within the valve, in combination withan annular stent and a sewing ring. The alternating cusps andcommissures mimic the natural contour of leaflet attachment.

A conventional heart valve replacement surgery involves accessing theheart in the patient's thoracic cavity through a longitudinal incisionin the chest. For example, a median sternotomy requires cutting throughthe sternum and forcing the two opposing halves of the rib cage to bespread apart, allowing access to the thoracic cavity and heart within.The patient is then placed on cardiopulmonary bypass which involvesstopping the heart to permit access to the internal chambers. Such openheart surgery is particularly invasive and involves a lengthy anddifficult recovery period.

Recently, a great amount of research has been done to reduce the traumaand risk associated with conventional open heart valve replacementsurgery. In particular, the field of minimally invasive surgery (MIS)has exploded since the early to mid-1990s, with devices now beingavailable to enable valve replacements without opening the chest cavity.MIS heart valve replacement surgery still typically requires bypass, butthe excision of the native valve and implantation of the prostheticvalve are accomplished via elongated tubes (catheters or cannulas), withthe help of endoscopes and other such visualization techniques. Someexamples of recent MIS heart valves are shown in U.S. Pat. No. 5,411,552to Anderson, et al., U.S. Pat. No. 5,980,570 to Simpson, U.S. Pat. No.5,984,959 to Robertson, et al., PCT Publication No. 00/047139 toGarrison, et al., and PCT Publication No. WO 99/334142 to Vesely.

The typical MIS valve of the prior art includes a directly radiallyexpanding stent that is initially compressed for delivery through acannula, and is then expanded at the site of implantation after removingthe constraint of the cannula. The expansion is accomplished using aninternal balloon catheter around which the stent is compressed.

Despite various delivery systems for conventional MIS valves, thereremains a need for a delivery system that more reliably controls theexpansion of new MIS valves.

SUMMARY OF THE INVENTION

In accordance with a preferred embodiment, the present inventionprovides a system for delivering and deploying an expandable prostheticheart valve, comprising a catheter shaft having a proximal end and adistal end and a lumen therethrough extending along an axis. The heartvalve deployment mechanism extends axially from the distal end of thecatheter shaft, and includes spaced apart proximal and distal deploymentmembers. An actuating shaft extends through the lumen of the cathetershaft and operates to actuate at least one of the proximal and distaldeployment members. The deployment members may be radially movable andcomprise fingers each pivoted at one end thereof to the deploymentmechanism. There are desirably at least two proximal deployment fingersand at least two distal deployment fingers, wherein the deploymentfingers are axially movable. The deployment members may be radiallymovable and there are two of the actuating shafts. A first actuatingshaft operates to radially displace the proximal deployment members anda second actuating shaft operates to radially displace the distaldeployment members, wherein the first and second actuating shafts areconcentrically disposed to slide with respect one another.

In one embodiment the deployment mechanism comprises a proximal colletwith respect to which the proximal deployment members pivot, and adistal collet with respect to which the distal deployment members pivot,wherein the proximal collet and distal collet are relatively axiallymovable. A first actuating shaft extends within a cavity in the proximalcollet and a first driver attaches thereto that acts upon the proximaldeployment members to pivot them with respect to the proximal collet. Asecond actuating shaft extends through the first actuating shaft andinto a cavity in the distal collet and a second driver attaches theretothat acts upon the distal deployment members to pivot them with respectto the distal collet.

There are various ways to actuate the deployment members. First, eachdeployment member may pivot about a point that is fixed with respect tothe associate collet and includes structure that engages cooperatingstructure on the associated driver, wherein axial movement of the driverrotates the structure about the pivot point, thus rotating thedeployment member. Alternatively, each deployment member has a pin fixedwith respect thereto that is received within a corresponding slot in theassociated driver, and each collet includes a plurality of pins fixedwith respect thereto that are received within corresponding slots in theassociated deployment members. In the alternative configuration, axialmovement of the driver displaces the pins fixed with respect to thedeployment members and causes the deployment members to pivot outwarddue to a camming action of the deployment member slots over the colletpins.

In a still further embodiment, each deployment member may comprise a padthat is coupled to a respective proximal and distal end cap disposedalong the catheter shaft, the pads being radially displaceable withrespect to the associated end cap, wherein the proximal and distal endcaps are axially movable with respect to each other. There may be two ofthe actuating shafts, each shaft controlling a plurality of flexibletongs having column strength that extend between one of the end caps andattach to the associated pads, wherein axial movement of each shaftshortens or lengthens the radial extent of the flexible tongs controlledthereby so as to radially displace the attached pads.

Still further, each deployment member may comprise a gear that engages agear track on the heart valve.

The system preferably includes a stabilization balloon on the cathetershaft proximal to the deployment mechanism and sized to expand andcontact a surrounding vessel adjacent the site of implantation. Thestabilization balloon may be shaped so as to permit blood flow past itin its expanded configuration, such as with multiple outwardly extendinglobes.

The heart valve deployment mechanism may be a modular unit coupled tothe distal ends of the catheter shaft and actuating shaft.

In another aspect of the invention, a system for delivering anddeploying a self-expandable prosthetic heart valve to a site ofimplantation is provided. The system comprises a catheter for advancingthe heart valve in a contracted configuration to the site ofimplantation; means on the catheter for permitting the heart valve toself-expand from its contracted configuration to an initial expandedconfiguration in contact with the surrounding site of implantation; andmeans for regulating the rate of self-expansion of the heart valve. Thesystem may also include means for expanding the heart valve from itsinitial expanded configuration to a final expanded configuration, suchas a balloon. Alternatively, the means for expanding the heart valvefrom its initial expanded configuration to a final expandedconfiguration may be the same as the means for regulating the rate ofself-expansion of the heart valve.

The means for expanding the heart valve from its initial expandedconfiguration to its final expanded configuration and the means forregulating the rate of self-expansion of the heart valve may comprise agear mechanism that engages both the distal and proximal ends of theheart valve. If the heart valve is of the rolled type having multiplewound layers, the gear mechanism may have a gear shaft that engages aninner layer of the spirally wound heart valve and a retaining bar thatengages an outer layer of the spirally wound heart valve, wherein thedistance between the gear shaft and retaining bar is adjustable.

Another aspect of the invention is a system for delivering and deployingan expandable prosthetic heart valve to a site of implantation,comprising a catheter for advancing the heart valve in a contractedconfiguration to the site of implantation, and a stabilization deviceprovided on the catheter sized to expand and contact a surroundingvessel adjacent the site of implantation. The system also has means onthe catheter distal to the stabilization device for expanding the heartvalve from its contracted configuration to an initial expandedconfiguration in contact with the surrounding site of implantation. Thestabilization device may be a balloon shaped so as to permit blood flowpast it in its expanded configuration, such as for example with multipleoutwardly extending lobes.

A method for delivering and deploying a self-expandable prosthetic heartvalve to a site of implantation is also provided by the presentinvention. The method comprises:

advancing the heart valve in a contracted configuration to the site ofimplantation;

permitting the heart valve to self-expand from its contractedconfiguration to an initial expanded configuration in contact with thesurrounding site of implantation; and

regulating the rate of self-expansion of the heart valve.

In the preferred method, the step of advancing the heart valve in acontracted configuration to the site of implantation comprises providinga heart valve deployment mechanism that in one operating mode maintainsthe heart valve in the contracted configuration, and in anotheroperating mode regulates the rate of self-expansion of the heart valve.The heart valve deployment mechanism may have a plurality of proximaldeployment members that engage a proximal end of the valve, and aplurality of distal deployment members that engage a distal end of thevalve, and wherein coordinated radial movement of the proximal anddistal deployment members regulates the rate of self-expansion of theheart valve. Alternatively, the heart valve deployment mechanismincludes a gear shaft having a plurality of gear teeth that engage agear track provided on the heart valve, wherein the rate ofself-expansion of the heart valve is regulated by regulating therotational speed of the gear shaft.

The preferred method further includes expanding the heart valve from itsinitial expanded configuration to a final expanded configuration. Also,a catheter-based valve deployment mechanism may be provided havingdeployment members that both regulate the rate of self-expansion of theheart valve and expand the heart valve from its initial expandedconfiguration to its final expanded configuration. Alternatively, acatheter-based valve deployment mechanism maybe provided havingdeployment members that regulate the rate of self-expansion of the heartvalve, and an inflation balloon expands the heart valve from its initialexpanded configuration to its final expanded configuration. In thelatter case, the valve inflation balloon is separate from the deploymentmechanism and is introduced into the valve after at least a partialexpansion thereof. The method further desirably includes stabilizing theheart valve in its contracted configuration adjacent the site ofimplantation prior to permitting the heart valve to self-expand. Thestep of stabilizing the heart valve may involve inflating astabilization balloon, and also permitting blood flow past the inflatedstabilization balloon.

A further understanding of the nature and advantages of the inventionwill become apparent by reference to the remaining portions of thespecification and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of an exemplary expandable heart valvedelivery and deployment system of the present invention with a cathetershaft shown broken so as to illustrate the main components thereof;

FIG. 2 is a perspective view of the distal end of the delivery system ofFIG. 1 showing a heart valve in its expanded configuration;

FIG. 3A is a longitudinal sectional view through a portion of the distalend of the delivery and deployment system of FIG. 1 illustrating part ofa mechanism for controlling the expansion of a heart valve, which isshown in its contracted configuration;

FIG. 3B is a longitudinal sectional view as in FIG. 3A showing the heartvalve expanded;

FIG. 4 is a perspective view of the distal end of an alternative heartvalve delivery and deployment system of the present invention showing aheart valve in its contracted configuration;

FIG. 5A is a perspective view of the delivery and deployment system ofFIG. 4 showing the heart valve in its expanded configuration and aninflated stabilization balloon;

FIG. 5B is a perspective view as in FIG. 5A illustrating a final step ofdeployment of the heart valve;

FIG. 6A is an enlarged elevational view of a portion of the distal endof the delivery and deployment system of FIG. 4;

FIG. 6B is an enlarged longitudinal sectional view of the portion of thedistal end of the delivery and deployment system seen in FIG. 6A;

FIGS. 7A-7F are perspective views showing a number of steps in thedelivery and deployment of an expandable heart valve using the system ofFIG. 4;

FIG. 8 is a perspective view of the distal end of a second alternativedelivery and deployment system of the present invention showing a heartvalve in its expanded configuration;

FIG. 9 is a perspective view of the distal end of the second alternativedelivery and deployment system shown as in FIG. 8 without the heartvalve;

FIG. 10 is a perspective view of the distal end of the delivery anddeployment system of FIG. 8 shown in a mode of operation that expandsthe heart valve outward into a locked position;

FIG. 10A is an enlarged sectional view of a portion of the distal end ofthe second alternative delivery and deployment system as taken alongline 10-10A of FIG. 10;

FIGS. 11A-11F are perspective views showing a number of steps in thedelivery and deployment of an expandable heart valve using the system ofFIG. 8;

FIG. 12 is a perspective view of the distal end of a third alternativedelivery and deployment system of the present invention that utilizes agearing mechanism and showing a heart valve in its expandedconfiguration;

FIG. 12A is an enlarged sectional view of a portion of the distal end ofthe third alternative delivery and deployment system as taken along line12A-12A of FIG. 12;

FIG. 13 is an enlarged perspective view of a portion of the delivery anddeployment system of FIG. 12 shown without the heart valve; and

FIG. 14 is a plan view of a stent of an expandable heart valve of thepresent invention for use with the third alternative delivery anddeployment system as seen in FIG. 12.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention discloses a number of expandable heart valves forimplantation in a host annulus, or host tissue adjacent the annulus. Thevalves may be implanted in any of the four valve positions within theheart, but are more likely to be used in replacing the aortic or mitralvalves because of the more frequent need for such surgery in thesepositions. The patient may be placed on cardiopulmonary bypass or not,depending on the needs of the patient.

A number of expandable prosthetic heart valves are disclosed inco-pending U.S. application Ser. No. 09/815,521 that are initiallyrolled into a tight spiral to be passed through a catheter or other tubeand then unfurled or unrolled at the implantation site, typically avalve annulus. These will be denoted “rolled heart valves” and compriseone- or two-piece sheet-like stent bodies with a plurality ofleaflet-forming membranes incorporated therein. Various materials aresuitable for the stent body, although certain nickel-titanium alloys arepreferred for their super-elasticity and biocompatibility. Likewise,various materials may be used as the membranes, including biologicaltissue such as bovine pericardium or synthetic materials. It should alsobe noted that specific stent body configurations disclosed herein or inU.S. application Ser. No. 09/815,521 are not to be considered limiting,and various construction details may be modified within the scope of theinvention. For example, the number and configuration of lockout tabs (tobe described below) may be varied.

As a general introduction, the heart valves in a first, spirally-woundor contracted configuration are delivered through a tube such as apercutaneously-placed catheter or shorter chest cannula and expelledfrom the end of the tube in the approximate implantation location. Theheart valve is then expanded into a second, unwound or expandedconfiguration that engages the native host tissue, such as the targetvalve annulus. Depending on the native valve being replaced, theprosthetic heart valve may have varying axial lengths. For example, inthe aortic position, an outflow portion of the valve may extend upwardinto and even flare out and contact the aorta to better stabilize thecommissure regions of the valve. In other words, the particular designof the valve may depend on the target valve location.

The present invention is particularly adapted for delivering anddeploying self-expandable rolled heart valves, although those of skillin the art will recognize that certain embodiments may be adapted fordeploying plastically deformable rolled heart valves. Self-expandablestents in general are known, typically constructed of a tubular metallattice that has a normal, relaxed diameter and is compressed forinsertion into a vein or artery. Upon expulsion from the end of acatheter, the tubular metal lattice expands to its original largerdiameter in contact with the vessel wall. It is important to note thatthere is no regulation of the self-expansion of the stent, as the tubereliably assumes its larger shape.

A number of embodiments of the present invention will now be describedwith reference to the attached drawings. It should be understood thatthe various elements of any one particular embodiment may be utilized inone or more of the other embodiments, and thus combinations thereof arewithin the scope of the appended claims.

FIG. 1 illustrates an exemplary system 20 for delivering and deployingan expandable heart valve. The main elements of the system 20 include aproximal operating handle 22, a catheter shaft 24 extending distallyfrom the handle and shown broken to fit on the page, a heart valvedeployment mechanism 26, and a guidewire 28 typically extending entirelythrough the system. The expandable heart valve 30 is seen held in acontracted configuration between a distal collet body 32 and a proximalcollet body 34 of the deployment mechanism 26. The system may furtherinclude a stabilization balloon 36 provided on the catheter shaft 24just proximal the deployment mechanism 26.

Prior to describing the exemplary deployment mechanism 26, andalternative mechanisms, in greater detail, an overview of the techniquesfor using the system 20 is appropriate. For this discussion, it will beassumed that the heart valve 30 will be implanted in the aorticposition.

Prior to introduction of the distal end of the system 20 into thepatient, the expandable heart valve 30 is selected based on ameasurement of the aortic annulus. Various sizing methodology areavailable, a discussion of which is outside the scope of the presentinvention. The selected heart valve 30 may be initially wound into atight spiral in its storage container, or it may be stored expanded andthen wound into its contracted configuration just prior to use. For thispurpose, co-pending U.S. application Ser. No. 09/945,392, now U.S. Pat.No. 6,723,122, entitled Container and Method for Storing and DeliveringMinimally-Invasive Heart Valves, filed Aug. 30, 2001, which is expresslyincorporated herein, may be used. That application discloses a systemfor storing and then automatically converting an expandable valve intoits contracted shape while still in the storage container. Additionally,the valve 30 may be stored along with the deployment mechanism 26 as amodular unit. In that case, the deployment mechanism 26 and valve 30 maybe snapped onto or otherwise coupled with the distal end of the cathetershaft 24. This enables one operating handle 22 and catheter shaft 24 tobe used with a number of different valve/deployment mechanism units.After those of skill in the art have an understanding of the variouscontrol or actuation shafts/cables described herein, the couplingstructure should be relatively straightforward, and thus a detailedexplanation will not be provided.

The guidewire 28 is first inserted into a peripheral artery, such as thefemoral or carotid, using known techniques, and advanced through theascending aorta into the left ventricle. The catheter shaft 24 with thedeployment mechanism 26 on its leading or distal end is then passed overthe guidewire 28, possibly with the assistance of an intermediate sizedobturator, and into the peripheral vessel via the well-known Seldingermethod. The operator then advances and positions the deploymentmechanism 26 in proximity to the implantation site, in this case theaortic annulus, using visualization devices such as radiopaque markerson the deployment mechanism 26 or heart valve 30, or an endoscope.Advancement of the deployment mechanism 26 involves simply pushing theentire catheter shaft 24 along the guidewire 28 using the handle 22.Once the valve 30 is properly positioned, the operator expands thestabilization balloon 36 into contact with the surrounding aorta. Inthis manner, the heart valve 30 is both axially and radially anchoredwith respect to the surrounding annulus to facilitate proper engagementtherewith. The stabilization balloon 36 may be shaped to permit bloodflow in its expanded configuration for beating heart surgeries.

Expansion of the heart valve 30 may be accomplished in various ways, aswill be described in greater detail below. Operation of the deploymentmechanism 26 involves manipulation of cables, shaft, or other elongateddevices passing from the operating handle 22 through the catheter shaft24. These elongated devices may be utilized to transfer axial(push/pull) forces or rotational torque initiated in the handle 22 tovarious elements of the deployment mechanism 26. The present applicationwill not focus on specific mechanisms in the handle 22 for initiatingthe forces on the cables or shafts passing through the catheter shaft24, as numerous such apparatuses are known in the art.

Now with reference to FIG. 2, the distal end of the delivery anddeployment system 20 is illustrated with the deployment mechanism 26holding the generally tubular heart valve 30. The heart valve 30 isshown in an expanded configuration with a portion cut away to illustratea lockout balloon 40 therewithin. The heart valve 30 has a rolledconfiguration and includes a generally sheet-like heart valve body 42that unwinds from a tight spiral into an expanded tube having a distalend 44 a and a proximal end 44 b. A plurality of distal deploymentmembers or fingers 46 extending proximally from the distal collet body32 engage the valve body distal end 44 a, while a plurality of proximaldeployment fingers 48 extending distal from the proximal collet body 34engage the valve body proximal end 44 b. It should be noted that variousfeatures of the heart valve 30, such as the valve leaflets, are notillustrated for clarity.

The inflated stabilization balloon 36 is shown having generally adisk-shape, although other shapes are contemplated, such as alobed-shape to permit blood flow, as will be described below. Across-section of the catheter shaft 24 illustrates a plurality of outerlumens 50 surrounding a central lumen 52. The lumens 50 may be used forinflating the balloon 36, 40, or for passing fluid or the devicestherethrough. The central lumen 52 is typically used for passage of thecables or shafts for operating the deployment mechanism 26.

FIGS. 3A and 3B illustrate in cross-section the details of the distalend of the deployment mechanism 26, and specifically the distal colletbody 32. FIG. 3A shows the heart valve body 42 in its contractedconfiguration with multiple spirally wound layers 60 a-60 e, while FIG.3B shows the valve body 42 in its expanded configuration having only onelayer 62. The distal deployment fingers 46 each possesses a flexibleclaw 64 that directly engages the outer layer 60 a of the valve body 42.The flexible claw 64 has an-initial curved set indicated in dashed linethat applies a radially inward spring force to the valve body 42. Whenin the position of FIG. 3A, the claw 64 flexes outward into a generallyliner configuration, and helps prevent damage to the valve body by thefingers 46, 48. At least two of the fingers 46, 48 on each end, andpreferably three or more, retain the valve body 42 in its spirally woundor contracted configuration during delivery through the vascular systemto the site of implantation. It should be noted also that the distalcollet body 32 has a rounded, generally bullet-shaped nose 66 thatfacilitates introduction into and passage through the vascular system.

As seen in FIG. 3A, each of the fingers 46 initially resides within anaxial channel 70 formed in the collet body 32 and pivots outward in aradial plane in the direction of arrow 72 about a collet pin 74 fixed inthe collet body across the channel. In the radially inward configurationof FIG. 3A, the fingers 46 are recessed within the channels 70 topresent a low introduction profile for the deployment mechanism 26. Eachof the fingers 46 includes a lever 76 that engages a depression 78within a distal driver 80. The driver 80 reciprocates axially within acavity 82 formed within the distal collet body 32, as indicated by thedouble-headed movement arrow 84. From the position shown, proximalmovement of the driver 80 with respect to the collet body 32 acts on thelever 76 to pivot the finger 46 outward in the direction of arrow 72.The lever 76 is shown rounded so as to easily slide within the similarlyshaped though concave depression 78. Of course, other arrangements forcoupling axial movement of the distal driver 80 to rotational movementof the finger 46 are possible.

A distal driver shaft 90 extends over the guidewire 28 to be fixedwithin a bore of the distal driver 80. Likewise, the distal collet shaft92 is concentrically disposed about the distal driver shaft 90 and isfixed within a bore of the distal collet body 32. All these elements arethus coaxial about the guide wire 28. Axial movement of the shafts 90,92 causes axial movement of the driver 80 and collet body 32,respectively. Collet movement is indicated by the double-headed arrow94. In the initial delivery configuration of FIG. 3A, the collet body 32is positioned distally from the distal end 44 a of the valve body 42.

In operation of the deployment mechanism 26 of FIG. 2, as best seen inFIG. 3B, the distal driver 80 is displaced within the cavity 82 byrelative movement of the distal driver shaft 90 and distal collet shaft92, and interaction between the lever 76 and depression 78 causesoutward pivoting motion of the finger 46. Because the valve body 42 isannealed into its expanded configuration, outward pivoting of thefingers 46 permits expansion thereof.

Therefore, the valve body 42 converts from its spirally woundconfiguration with multiple spirally-wound layers 60 a, 60 e as seen inFIG. 3A, to the expanded configuration of FIG. 3B having the singlelayer 62. During this expansion, contact between the flexible claws 64and the outer layer 60 a of the valve body 42 is maintained bycontrolling the relative movement between the distal driver 80 and thedistal collet body 32. This contact between the claws 64 and valve body42 regulates the speed or rate of expansion of the valve body, thuspreventing any mis-alignment problems. That is, because of the provisionof both the distal collet body 32 and proximal collet body 34, andassociated fingers 46 and 48, the rate of expansion of both the distalend 44 a and proximal end 44 b of the valve body 42 can be equilibrated.Because both ends of the valve body 42 expand at the same rate, thevalve forms a tube rather than potentially expanding into a partial coneshape.

It is important to note that during transition of the valve body 42 fromits contracted to its expanded configuration, the distal collet body 32moves in a proximal direction with respect to the valve body 42 asindicated by the movement arrow 96. The reader will note the differentrelative positions of the proximal end of the collet body 32 withrespect to the distal end 44 a of the valve body 42 in FIGS. 3A and 3B.This collet body 32 movement results from relative movement of thedistal collet shaft 92 with respect to the valve body 42, which bodyposition is determined by the position of the proximal fingers 48, or bya supplemental shaft (not shown) coupled to the operating handle 22.Because of the proximal collet body 32 movement with respect to thevalve body 42, the flexible claws 64 maintain the same axial positionwith respect to the valve body 42 during outward pivoting of the fingers46. That is, outward pivoting of the fingers 46 causes both radiallyoutward and distal axial movement of the claws 64 with respect to colletpin 74, and the axial component of movement must be accommodated bymovement of the collet body 32 or else the claws 64 would disengage thevalve body 42. The distal collet body 32 includes a frusto-conicalproximal end 98 that facilitates displacement of the collet body intothe partially unwound valve body 42, and prevents binding therebetween.

The valve body 42 expands outward under regulation of the fingers 46, 48until it contacts the surrounding host tissue. The valve body 42 has anannealed shape such that its relaxed configuration is open, with itsinner and outer side edges being spaced apart. As such, the valve body42 will continue to expand until it contacts the surrounding tissue, aslong as the final tubular size of the valve is larger than the site ofimplantation. Therefore, proper sizing of the valve is extremelyimportant.

Once the valve body 42 contacts the surrounding tissue, it has reachedits initial expanded state. At this stage, the deployment fingers 46, 48remain outwardly pivoted but are moved apart by relative axial movementof the collet bodies 32, 34 away from each other so as to disengage theclaws 64 from the distal and proximal ends 44 a, 44 b of the valve body42. Once disengaged from the valve, the fingers 46, 48 may be retractedinto their respective channels 70. Subsequently, inflation of thelockout balloon 40 (FIG. 2) further expands the valve body 42 into moresecure engagement with the surrounding tissue until lockout features onthe valve body engage and secure the valve body in its final expandedconfiguration. These lockout features are fully described in co-pendingU.S. application Ser. No. 09/815,521, which disclosure is herebyexpressly incorporated by reference.

The lockout balloon 40 resides initially in the catheter shaft 24 oreven outside of the body during the first phase of expansion of thevalve body 42. Because the valve body 42 advances through thevasculature in a relatively tight spiral so as to minimize its radialprofile for minimally invasive surgeries, the lockout balloon 40 ispreferably not positioned in the middle thereof. Of course, thisconstraint is necessary only when the insertion space is limited, and ifthe surgery is open heart or otherwise not so space-limited then theballoon 40 may indeed be initially positioned inside and delivered alongwith the valve. In the preferred minimally invasive deployment, however,the balloon must be introduced within the valve body 42 after at least apartial expansion or unwinding thereof. Typically, the valve body 42expands into its initial expanded configuration in contact with thesurrounding tissue before the lockout balloon 40 advances into itsposition as seen in FIG. 2, although the balloon may be advanced intothe valve as soon as a sufficient space in the middle of the valve opensup.

The lockout balloon 40 preferably has a shape with enlarged ends and aconnecting middle portion, much like a dumbbell. In this manner, theballoon acts on the proximal and distal ends of the valve body 42,without contacting a middle portion where the leaflets of the valve arelocated. Of course, other arrangements of balloon are possible, as aremultiple lockout balloons.

After the valve body 42 is fully implanted, the lockout balloon 40 isdeflated and the catheter shaft 24 withdrawn from the body along theguide wire 28. The proximal collet body 34 also has a bullet-shapedproximal end to facilitate this removal through the vasculature.

FIGS. 4-6B illustrate the distal end of an alternative expandable heartvalve delivery and deployment system 100 of the present invention thatis in many ways similar to the first-described embodiment of FIGS. 1-3B.Namely, as seen in FIG. 4, the system 100 includes a deploymentmechanism 102 having a distal collet 104 with a plurality of deploymentmembers or fingers 106, and a proximal collet 108 having a plurality ofdeployment members or fingers 110. The deployment fingers 106, 110engage respective ends of a self-expandable heart valve 112, which isshown in its contracted configuration. As in the earlier embodiment, thedeployment fingers 106, 110 enable regulated self-expansion of the heartvalve 112 to ensure the valve expands to the correct tubular shape.Although there are a number of constructional differences between thetwo embodiments, the main functional difference pertains to the mannerin which flexible claws 114, 116 of the deployment fingers 106, 110 aremaintained in particular axial locations with respect to the distal andproximal ends 118 a, 118 b, respectively, of the valve 112. In thefirst-described embodiment, the collets 32, 34 were axially displacedalong with the drivers 80, thus necessitating axial movement andcoordination of four different shafts, while in the embodiment of FIGS.4-6B movement of only two shafts are needed. This modification willbecome clear below.

FIG. 4 illustrates a stabilization balloon 120 in its folded or deflatedconfiguration just proximal to proximal collet 108. FIG. 5A shows thestabilization balloon 120 inflated and assuming a four-lobed star shape.The entire distal end of the system 100 is positioned at the distal endof a catheter shaft 122 and travels over a guide wire 124. Thestabilization balloon 120 is sized to expand and contact a surroundingvessel adjacent the site of implantation, such as the ascending aorta.The star shape of the stabilization balloon 120 permits blood flow inthe expanded configuration of the balloon for beating heart surgeries,though of course other balloon shapes could be used. Furthermore,devices other than a balloon for stabilizing the distal end of thesystem 100 may be utilized. For example, a mechanical expandingstructure having struts or a wire matrix may work equally as well as aballoon and also permit blood flow therethrough. Therefore, the termstabilization device refers to all of the above variants.

FIG. 5A also illustrates the heart valve 112 in its initial expandedconfiguration such that a plurality of leaflet mounting windows 126 arevisible. In this case, the leaflets are not shown for clarity so as toexpose a distal collet shaft 128 extending through the middle of thevalve between the proximal and distal collets 104, 108. The heart valve112 is permitted to expand into the shape shown in FIG. 5A by outwardpivoting of the respective flexible claws 114, 116 of the deploymentfingers 106, 110. This pivoting occurs by proximal movement of a distaldriver 130 with respect to the distal collet 104, and distal movement ofa proximal driver 132 with respect to the proximal collet 104. Thechange in the relative positions of the drivers 130, 132 and collets104, 108 may be seen by comparison of FIG. 4 and FIG. 5A.

FIG. 5B shows the deployment mechanism 102 during a valve deploymentphase that converts the valve 112 from its initial expandedconfiguration to a final expanded or locked out configuration. Thedeployment fingers 106, 110 have been displaced so that they residewithin the tubular valve 112 and are then in a position to be once againpivoted outward, as indicated by the arrows 134, into contact with thevalve. In this case, therefore, a separate lockout balloon within thevalve 112, such as balloon 40 in FIG. 1, may not be necessary, unlessthe additional expansion force is required. A full sequence of operationof the deployment system 100 will be described below with respect toFIGS. 7A-7F after an exemplary construction of the system is explained.

FIGS. 6A and 6B illustrate, in elevational and sectional views,respectively, the proximal end of the deployment system 102 with thefingers 110 pivoted open to an intermediate position during the stage ofself-expansion of the valve 112 from its contracted configuration to itsinitial expanded configuration. The flexible claws 116 are shown incontact with the exterior of the valve body 112, with their curved setshown in phantom. The direction of movement of the fingers 110 isindicated in both views by the movement arrow 136.

With specific reference to FIG. 6B, the collet 108 includes a centralthrough bore (not numbered) that slidingly receives the distal colletshaft 128. The distal collet shaft 128, in turn, slidingly receives adistal driver shaft 140, which directly travels over the guidewire 124.Each of the deployment fingers 110 resides within an axial colletchannel 144 that extends from the distal end of the collet 108 intoproximity with a cavity 146 located on the proximal end. The proximaldriver 132 reciprocates within the cavity 146 and includes a throughbore (not numbered) that slides over a tubular boss 148 extendingproximally from the collet 108. The driver 132 includes a proximaltubular flange 150 that closely receives and is fixed with respect to aproximal driver shaft 152. A proximal collet shaft 154 mounts to theexterior of the tubular boss 148 of the collet 108, and is adapted toslide within the proximal driver shaft 152. By virtue of the four shafts128, 140, 152, and 154, the collets 104, 108 and drivers 130, 132 may beaxially displaced with respect to one another.

The proximal collet 108 carries a plurality of collet pins 116 that arefixed across an approximate midpoint of each of the collet channels 144and are received within curved finger cam slots 162. As mentionedpreviously, two, and preferably three fingers 110 are required forreliable regulation of the self expansion of the valve 112, and thereare an equivalent number of collet channels 144 and pins 160. The fingercam slots 162 are disposed in the middle of each finger 110, and thefinger also carries a pin 166 fixed to its proximal end. As seen best inFIG. 6A, each finger pin 166 travels along a curvilinear collet cam slot168. The finger pins 166 are each also constrained by a linear drivertravel slot 170 that is best seen in FIG. 6B. With reference again toFIG. 6A each finger 110 includes a flange portion 172 that is receivedin a driver channel 174 formed between bifurcated walls 176 of theproximal driver 132. The driver travel slot 170 is thus formed in bothwalls 176.

Movement of the various components of the proximal end of the deploymentmechanism 102 is depicted in FIG. 6B. The outward pivoting motion of thefinger 110 is indicated by arrow 136. The outward finger movement isaccomplished by distal movement of the finger 110 with respect to thecollet pin 160 which travels from the upper right end of the finger camslot 162 to the lower left end. Because the collet pin 160 is fixed withrespect to the collet 108, the finger 110 moves outward by the cammingaction of the pin 160 within the slot 162. Distal movement of the finger110 is caused by movement in the distal direction of the driver 132 withrespect to the collet 108, as indicated by arrow 180, due to theengagement between the driver travel slot 170 and the finger pin 166. Asthe finger pin 166 moves in the distal direction, it travels along thecurvilinear collet cam slot 168. The linear driver travel slot 170accommodates radially inward movement of the finger pin 166 in thisregard.

The shapes of the finger cam slot 162 and collet cam slot 168 aredesigned such that the claw 116 at the distal end of the finger 110moves radially outward but remains in the same axial position.Furthermore, this movement of the finger 110 is accomplished bymaintaining the proximal collet 108 in a fixed relationship with respectto the valve body 112, while only displacing the proximal driver 132 ina distal direction, indicated by arrow 180. As such, only the proximaldriver cable 152 need be displaced. In the same manner, only the distaldriver shaft 140 need be displaced with respect to the distal colletshaft 128 to actuate the distal deployment fingers 106 (FIG. 4). Indeed,the distal and proximal collets 104, 108 remain stationary with respectto the valve 112 while the distal and proximal drivers 130, 132 aredisplaced toward one another. Likewise, the fingers 106, 110 areretracted radially inwardly by opposite movement of the drivers 130,132.

A sequence of steps in the delivery and deployment of a heart valveutilizing the deployment mechanism 102 of FIG. 4 is seen in FIGS. 7A-7F.FIG. 7A shows the deployment mechanism and heart valve in their radiallycontracted configurations such that the entire assembly resembles anelongated bullet for easy passage through the vasculature of thepatient, which is indicated by a generic vessel 190. After reaching thesite of implantation, the valve 112 is permitted to self expanded undercontrol of the deployment fingers. Namely, the proximal and distaldrivers move axially toward one another permitting the fingers to pivotopen which in turn allows the spirally wound expandable heart valve tounwind. The heart valve unwinds at a controlled rate into its initialexpanded configuration in contact with the surrounding tissue, asexplained above.

Now with reference to FIG. 7C, the distal and proximal collets areaxially displaced away from one another so that the claws at the end ofthe fingers release from the ends of the heart valve. Subsequently, asseen in FIG. 7D, movement of the proximal and distal drivers away fromone another and with respect to the associated collets retracts thefingers inward a slight amount. FIG. 7E shows the deployment mechanismafter the collets have been axially advanced toward one another suchthat the claws at the end of the fingers are disposed within the heartvalve. In a final deployment step, as seen in FIG. 7F, the proximal anddistal drivers are again advanced toward one another and with respect tothe stationary collets so that the fingers pivot outward into contactwith the interior of the valve. The fingers force the valve outwardagainst the surrounding vessel and into its locked position. Thedeployment mechanism is then removed from the body by retracting thedeployment fingers and pulling the catheter along the guide wire.

FIGS. 8-10A illustrates a second alternative heart valve delivery anddeployment system 200 of the present invention that operates in much thesame manner as the first two embodiments described above, althoughwithout pivoting deployment members. FIG. 8 illustrates the distal endof the system 200 with an expandable heart valve 202 held therewithin inits initial expanded configuration. FIG. 9 illustrates the distal end ofthe system 200 in the same configuration but without the heart valve.The system 200 includes a valve deployment mechanism 204 having aplurality of distal deployment pads 206 and a plurality of proximaldeployment pads 208 that engage the valve 202. The pads 206, 208 areshown in FIG. 8 on the exterior of the valve that enables theaforementioned control of the valve self-expansion. The pads 206,208 aredesirably relatively rigid and have rounded edges and/or are otherwisecoated with a material that prevents damage to the valve 202.

With specific reference to FIG. 9, each of the distal pads 206(preferably three) couples to a distal end cap 210 via a tension spring212. Likewise, each of the proximal pads 208 (preferably three) couplesto a proximal end cap 214 via a tension spring 216. The springs 212, 216exert radially inward forces on each of the pads 206, 208. The end caps210, 214 are mounted on separately movable shafts such that their axialspacing may be varied.

FIG. 10 illustrates the deployment mechanism 204 in a deployment stagethat converts the heart valve from its initial expanded configuration toits final, locked out configuration. FIG. 10A is a longitudinalsectional view taken along line 10A-10A of FIG. 10 and shows in detailthe various components of the distal end of the deployment mechanism204. The distal end cap 210 is shown having a recess in its distal endthat houses a plurality of shafts 220 about which coils each tensionspring 212. The radial position of each pad 206 is controlled by use ofa distal wire tong 222 that is highly flexible but possesses columnstrength. Various nickel-titanium alloys are well-suited for use as thewire tongs 222. Each tong 222 attaches to an inner side of a distal pad206 and extends radially inward through a 90 degree channel formed inthe distal end cap 210 into fixed engagement with a tong driver 224. Thetong driver 224 attaches to a tong driver shaft 226 and is adapted foraxial movement within the mechanism 204. The tong driver shaft 226 fitsclosely and is linearly slidable over a distal end cap shaft 228 fixedto a bore in the end cap 210. The distal end cap shaft 228 includes alumen that closely receives a guidewire (not shown) used in positioningthe heart valve at the site of implantation.

For the purpose of describing radial movement of the distal pads 206with reference to FIG. 10A, the reader will ignore the interposition ofa plurality of expansion bars 230 and brace links 232. Initially, thetong driver 224 is positioned to the right of where it is located inFIG. 10A and toward a distal slide collar 234. As such, the majority ofthe distal wire tong 222 is pulled through the distal end cap 210 suchthat its radial length is minimized, in contrast to the illustration.Therefore, the distal pads 206 are pulled radially inward and constrainthe heart valve in its spirally wound configuration. During regulatingself-expansion of the valve, the tong driver shaft 226 is advanced inthe distal direction with respect to the end cap shaft 228 such that thetong driver 224 moves to the left, pushing the distal wire tongs 222radially outward. Because of the column strength of the wire tongs 222,this operation forces the distal pads 206 radially outward against theinward forces of the tension springs 212, and permits the spirally woundvalve to unwind.

The final outward position of the distal and proximal pads 206, 208 isseen in FIG. 9. FIG. 9 also illustrates the distal tong shaft 226 andthe distal end cap shaft 228, along with a proximal tong shaft 236 and aproximal end cap shaft 238. Again, regulated self-expansion of the heartvalve is accomplished by holding the end cap shafts 228, 238 stationery,while displacing the tong shaft 226, 236 away from one another. Becausethe pads 206, 208 displace directly radially outward, there is no needfor any accommodating axial movement as with the earlier pivoting fingerembodiments.

After permitting the heart valve 202 to self-expand to its initialexpanded configuration as seen in FIG. 8, the pads 206, 208 arerepositioned inside the valve and displaced outward to force the valvefurther outward into its final, expanded configuration. The position ofthe deployment mechanism 204 in this phase of the deployment operationis seen in FIGS. 10 and 10A. It will be noted that various components ofthe distal end of the deployment mechanism 204 will be numbered the sameon the proximal end.

As seen in FIG. 10A, each of the expansion bars 230 pivots at one endabout a point 239 on the respective slide collar 234. The opposite endof each expansion bar 230 is free to pivot radially outward into contactwith the inner side of one of the pads 206, 208. Each brace link 232pivots at one end about a point 240 at the midpoint of an expansion bar230, and at the other and about a pivot point 242 fixed with respect toone of the end caps 210. Axial movement of the end caps 210 toward oneanother causes the expansion bars 230 to pivot outward by virtue oftheir connection to the end caps through the brace links 232. Thisumbrella-like expansion structure provides substantial strength inforcing the heart valve 202 into its locked out position.

FIGS. 11A-11F illustrate several stages in the use of the secondalternative deployment mechanism 204 to deliver and deploy the heartvalve 202. FIG. 11A shows the assembly in its radially contractedconfiguration for delivery through the patient's vasculature. FIG. 11Billustrates release of the wire tongs to push the pads radially outwardwhich permits controlled self-expansion of a heart valve to its initialexpanded configuration. In FIG. 11C, the end caps are axially displacedaway from one another so that the pads disengage from the heart valve.In this regard, the tension provided by springs 212, 216 on the pads206, 208 provides an axial force that helps disengage the pads frombetween the valve and the surrounding tissue. At this stage, the wiretongs remain pushed radially outward. FIG. 11D shows the end caps in thesame axial position but after the wire tongs have been retracted suchthat the tension springs pull the pads inward. In FIG. 11E, the end capsare displaced axially toward one another which causes the expansion barsto pivot outward, and in addition, the pads moved inside the valve.Finally, FIG. 11F shows further end cap movement toward each other suchthat the expansion bars push the pads radially outward in conjunctionwith movement of the wire tongs so as to further expand the valve intoits locked out configuration.

FIGS. 12-13 illustrate the distal end of a further alternative heartvalve delivery and deployment system 300 that utilizes a gearingmechanism to expand a heart valve 302 into its initial and finalexpanded configurations. The system includes a deployment mechanism 304at the distal end of a shaft 306 having a distal end keeper 308 andretaining bar 310 and a proximal end keeper 312 and retaining bar 314.The axial spacing between the distal and proximal end keepers 308, 312may be varied by movement of a connecting rod 316 (FIG. 12A) about whicha gear shaft 318 rotates. The heart valve 302 includes a sheet-likestent body bordered by a distal end 320, a proximal end 322, an outerside edge 324, and an inner side edge (not shown). The stent bodyfurther includes a distal gear track 326 extending circumferentiallyadjacent the distal end 320 and a proximal gear track 328 extendingcircumferentially adjacent the proximal end 322. The assembly rides overa guide wire 330 as mentioned previously.

With reference to FIGS. 12A and 13, details of the distal end keeper 308and retaining bar 310 will be described. The retaining bar 310 extendsaxially in a proximal direction from the end keeper 308 includes aninwardly formed tab 340 that engages a retaining slot 342 in an outervalve body winding 344 adjacent to the outer side edge 324. FIG. 12Aillustrates in cross-section an inner winding 346 spaced from the outerwinding 344 by a distance A. Of course, there may be more than twowindings of the valve body in the contracted configuration thereof, aspreviously illustrated, for example, in FIG. 3A. Therefore, the distanceA varies as the valve unwinds.

The gear shaft 318 includes gear teeth 350 positioned to engage thedistal gear track 324. In a similar manner, a second set of gear teeth(not shown) is provided on the proximal end of the gear shaft 318 toengage the proximal gear track 326. As mentioned, the gear shaft 318rotates about the connecting rod 316, which is held by a shaft retainer352 in a winding variance slot 354 in the distal end keeper 308. The endof the connecting rod 316 includes a flat or other such feature thatregisters with a cooperating feature in the winding variance slot 354 toprevent rotation of the rod, and provide a counter-torque to rotation ofthe gear shaft 318. The slot 354 is elongated in the radial direction topermit radial movement of the connecting rod 316 and accompanying gearshaft 318. Provision of a pusher 356 spring loaded against theconnecting rod 316 by a spring 358 and set screw 360 maintains the gearteeth 350 in engagement with the gear track 324.

With reference to FIG. 12, it can be seen that the deployment mechanism304 remains circumferentially fixed with respect to the outer side edge324 by virtue of the engagement between the retaining bar tabs 340 andretaining slots 342. The gear shaft 318, on the other hand,circumferentially displaces the inner winding 346 in a direction thatunwinds the valve from its contracted configuration to its expandedconfiguration. During the unwinding process, the distance A between theouter winding 34 and the inner winding 346 is regulated by the springloaded pusher 356. The valve 302 may be converted to its initialexpanded configuration, and then further balloon expanded to a finallockout position, or the deployment mechanism 304 can fully expand thevalve into its lockout position. When the deployment mechanism 304 is nolonger needed, the end keepers 308, 312 are displaced axially apart suchthat the retaining bars 310, 314 disengage from their respectiveretaining slots 342. The deployment mechanism 304 can then be pulledover the guide wire 330 from within the deploying valve.

One advantage of such a deployment system 300 that utilizes a gearingmechanism is that both unwinding and winding of the valve 302 maybeeasily controlled. Therefore, the surgeon may initially expand the valve302 but then contract it somewhat to modify its position prior tolocking it into its final expanded shape. In the worst case, the valve302 may be completely contracted into its thin profile and removed fromthe patient if desired, such as if the sizing is not optimal or fromother complications.

FIG. 14 illustrates in plan view an exemplary aortic valve body 400 foruse with a deployment mechanism similar to that shown in FIG. 12. Thevalve body 400 includes a distal end 402, a proximal end 404, an innerside edge 406, and an outer side edge 408. A distal gear track 410 isshown adjacent the distal end 402, while a proximal gear track 412extends along an outflow band 414. A plurality of leaflet openings 416is provided between the distal end 402 in the outflow band 414. A flaredmesh 418 separates the outflow band 414 from the proximal end 404. Asupplemental gear track 420 is provided adjacent the proximal end 404.The distal, proximal, and supplemental retaining slots 422, 424, 426 arelocated adjacent the outer side edge 408 and receive respectiveretaining tabs from the retaining bars of the deployment mechanism.Finally, lockout tabs 430 are provided to engage lockout channels 432and maintain the valve in its expanded configuration.

In contrast to the valve 302 shown FIG. 12, the flared mesh 418 extendsin the outflow direction and may be used to engage the ascending aorta.To facilitate flaring of the mesh 418 during deployment of the valve,the supplemental gear track 420 has a smaller number of openings perlength than the distal or proximal gear tracks 410, 412. Likewise, thegear shaft utilized in deploying the valve body 400 has three sets ofgear teeth, one of which has fewer teeth per rotation so as to mate withthe supplemental gear track 420. In this manner, the proximal end 404 isexpanded at a faster rate then either the distal end 402 or outflow band414 such that it flares outward with respect thereto.

While the foregoing describes the preferred embodiments of theinvention, various alternatives, modifications, and equivalents may beused. Moreover, it will be obvious that certain other modifications maybe practiced within the scope of the appended claims.

1. A system for delivering and deploying an expandable prosthetic heartvalve, comprising: an expandable prosthetic heart valve including astent body having a plurality of biological tissue leaflets incorporatedtherein; a catheter shaft having a proximal end and a distal end and alumen therethrough extending along an axis; a heart valve deploymentmechanism extending axially from the distal end of the catheter shaft,the deployment mechanism including spaced apart proximal and distaldeployment members for regulating self-expansion of the prosthetic heartvalve, the proximal deployment member configured to apply a radiallyinward force along a proximal end portion of the stent body while theproximal deployment member engages an outer surface of the proximal endportion, and the distal deployment member configured to apply a radiallyinward force along a distal end portion of the stent body while thedistal deployment member engages an outer surface of the distal endportion; and an actuating shaft extending though the lumen of thecatheter shaft operable to actuate at least one of the proximal anddistal deployment members.
 2. The system of claim 1, wherein thedeployment members are radially movable and comprise fingers eachpivoted at one end thereof to the deployment mechanism.
 3. The system ofclaim 2, wherein there are at least two proximal deployment fingers andat least two distal deployment fingers, and wherein the deploymentfingers are axially movable.
 4. The system of claim 1, wherein thedeployment members are radially movable and there are two of theactuating shafts, a first actuating shaft being operable to radiallydisplace the proximal deployment members and a second actuating shaftbeing operable to radially displace the distal deployment members, andwherein the first and second actuating shafts are concentricallydisposed to slide with respect one another.
 5. The system of claim 1,wherein the deployment mechanism comprises a proximal collet withrespect to which the proximal deployment members pivot, and a distalcollet with respect to which the distal deployment members pivot, andwherein the proximal collet and distal collet are relatively axiallymovable.
 6. The system of claim 5, further including a first actuatingshaft extending within a cavity in the proximal collet and a firstdriver attached thereto that acts upon the proximal deployment membersto pivot them with respect to the proximal collet, and a secondactuating shaft extending through the first actuating shaft and into acavity in the distal collet and having a second driver attached theretothat acts upon the distal deployment members to pivot them with respectto the distal collet.
 7. The system of claim 6, wherein each deploymentmember pivots about a point that is fixed with respect to the associatedcollet and includes structure that engages cooperating structure on theassociated driver, and wherein axial movement of the driver rotates thestructure about the pivot point, thus rotating the deployment member. 8.The system of claim 1, further including a stabilization balloonprovided on the catheter shaft proximal to the deployment mechanism andsized to expand and contact a surrounding vessel adjacent the site ofimplantation.
 9. The system of claim 1, wherein the heart valvedeployment mechanism is a modular unit coupled to the distal ends of thecatheter shaft and actuating shaft.
 10. The system of claim 1, wherein:the distal deployment member comprises distal fingers extendingproximally toward a distal region of engagement with the stent body; andthe proximal deployment member comprises proximal fingers extendingdistally toward a proximal region of engagement with the stent body;wherein the proximal and distal fingers are configured to engage andlimit expansion of the stent body.
 11. A system for delivering anddeploying a self expandable prosthetic heart valve to a site ofimplantation, comprising: a self-expandable prosthetic heart valveincluding: a self-expandable valve body having a plurality of biologicaltissue leaflets incorporated therein; a catheter for advancing the selfexpandable prosthetic heart valve in a contracted configuration to thesite of implantation; means on the catheter for permitting the heartvalve to self expand from its contracted configuration to an initialexpanded configuration in contact with the surrounding site ofimplantation; and means for applying an inward radial force along thevalve body while engaging an outer surface of the valve body, forregulating the rate of self-expansion of the heart valve such thatproximal and distal ends of the valve body are expanded together,thereby allowing the valve body to maintain a generally tubular shapeduring self-expansion.
 12. The system of claim 11, further including:means for expanding the heart valve from its initial expandedconfiguration to a final expanded configuration.
 13. The system of claim12, wherein the means for expanding the heart valve from its initialexpanded configuration to a final expanded configuration comprises aballoon.
 14. The system of claim 11, further including a stabilizationdevice provided on the catheter proximal to the means on the catheterfor permitting the heart valve to self-expand, the device being sized toexpand and contact a surrounding vessel adjacent the site ofimplantation.
 15. The system of claim 11, wherein the means for applyingthe inward radial force comprises: distal fingers extending proximallyfrom a distal portion of the means for permitting; and proximal fingersextending distally from a proximal portion of the means for permitting;wherein the proximal and distal fingers are configured to engage andlimit expansion of the heart valve.
 16. A method for delivering anddeploying a self-expandable prosthetic heart valve to a site ofimplantation, comprising: advancing the heart valve in a contractedconfiguration to the site of implantation; permitting the heart valve toself-expand from its contracted configuration to an initial expandedconfiguration in contact with the surrounding site of implantation; andregulating the rate of self-expansion of the heart valve by applying aninward radial force against outer surfaces of proximal and distal endsof the heart valve such that the expansion rates of the proximal anddistal ends of the heart valve are equilibrated.
 17. The method of claim16, wherein the step of advancing the heart valve in a contractedconfiguration to the site of implantation comprises providing a heartvalve deployment mechanism that in one operating mode maintains theheart valve in the contracted configuration, and in another operatingmode regulates the rate of self-expansion of the heart valve.
 18. Themethod of claim 17, wherein the heart valve deployment mechanismincludes a plurality of proximal deployment members that engage aproximal end of the valve, and a plurality of distal deployment membersthat engage a distal end of the valve, and wherein coordinated radialmovement of the proximal and distal deployment members regulates therate of self-expansion of the heart valve.
 19. The method of claim 18,wherein the deployment members comprise fingers that pivot, and whereinthe method includes regulating the rate of pivot of the deploymentmembers to regulate the rate of self-expansion of the heart valve. 20.The method of claim 19, wherein the heart valve deployment mechanismincludes a proximal collet about which the proximal fingers pivot and adistal collet about which the distal fingers pivot, and wherein themethod includes displacing the proximal and distal collets axiallyduring pivoting of the proximal and distal fingers.
 21. The method ofclaim 16, further including: expanding the heart valve from its initialexpanded configuration to a final expanded configuration.
 22. The methodof claim 21, further including providing a catheter-based valvedeployment mechanism having deployment members that regulate the rate ofself-expansion of the heart valve and an inflation balloon that expandsthe heart valve from its initial expanded configuration to its finalexpanded configuration.
 23. The method of claim 22, wherein the valveinflation balloon is separate from the deployment mechanism and isintroduced into the valve after at least a partial expansion thereof.24. The method of claim 16, further including: stabilizing the heartvalve in its contracted configuration adjacent the site of implantationprior to permitting the heart valve to self-expand.
 25. The method ofclaim 24, wherein the step of stabilizing the heart valve comprisesinflating a stabilization balloon.
 26. The method of claim 16, whereinthe regulating further comprises applying the inward radial force with aplurality of projections that extend axially toward each other fromaxially spaced locations along an axis of the heart valve.
 27. A systemfor delivering and deploying an expandable prosthetic heart valve,comprising: an expandable prosthetic heart valve; a catheter shafthaving a proximal end and a distal end and a lumen therethroughextending along an axis; a heart valve deployment mechanism extendingaxially from the distal end of the catheter shaft, the deploymentmechanism including spaced apart proximal and distal deployment membersconfigured to move radially and engage outer surfaces of the heart valvewhile limiting self expansion of the prosthetic heart valve; anactuating shaft extending through the lumen of the catheter shaftoperable to actuate at least one of the proximal and distal deploymentmembers, wherein the heart valve deployment mechanism is a modular unitstored with the prosthetic heart valve and coupled to the distal ends ofthe catheter shaft and actuating shaft at the time of delivery.
 28. Thesystem of claim 27, wherein the deployment members comprise fingers eachhaving a first end and a second end, wherein the first end is pivotallycoupled to the deployment mechanism and the second end is configured toengage the prosthetic heart valve for selectively limitingself-expansion.
 29. The system of claim 27, wherein the deploymentmechanism comprises a proximal collet with respect to which the proximaldeployment members pivot, and a distal collet with respect to which thedistal deployment members pivot, and wherein the proximal collet anddistal collet are relatively axially movable.
 30. The system of claim27, wherein: the distal deployment member extends proximally toward aregion of engagement with the heart valve; and the proximal deploymentmember extends distally toward a region of engagement with the heartvalve.